Armature



J.W..PEARS0N. ARMATURE. I 6' APPLICATION mm man la:

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APPLICATION FILED AUGJ, 1916.

Patented Nov. 4,1919.

3 $HEETSSHEET 2.

J. w. PEARSON;

ARMATURE.- APPLICATION men/mm. 191s.

Patented Nov. 4, 1919.

- 3 SHEETS-SHEET 3 WEGJISESZ JOHN PEARSON OF CHICAGO, ILLINOIS.

ARMATURE.

Specification of Letters Patent.

Patented Nov. 4, 1919.

Application am August 7, 1916. Serial No. 113,614

To all whom it may concern:

Be it known that I, 'JOl IN W. PEnRsoN, a citizen of the United States of America, and

a resident of Chicago, county of Cook, and

State of Illinois, "have invented certain new and useful Improvements in Armatures, of which the followin is a specification.

. This invention re ates to dynamo-electric machinery, :and more particularly to-the arrangement and insulation of the windings on the armature. a

The main objects of this invention'are'to provide an improved form of direct current armature adapted for use in a small motor which must receive its power directly from a high voltage source, such for instance, as used in direct current railway service, where the voltage ranges, from five hundred to seven hundred volts, and where as a factor of safety 300 volts is added to the maximum operating voltage, making a test condition of 1000 volts direct current; to provide an improved form and arrangement of armature insulation and means. for holding the several coils in place respectively; and to so arrange and insulate .the coils of a drum winding on a slot wound armature as to.

permit of operating" the machine on high voltage without danger of rupturing the in- 1 sulation or shorting coils.

An illustrative embodiment of this iniven-. 'tion is shown in the accompanying drawings, in which Figure 1 is a side view of the armature.

Fig.- 2 is an end view from the right of Fig.1.

Fig. 3 is an end view from the left of Fig- 1. .l i

Fig. 1 is an axial section on the line A-A of Fig. 1, the windings being omitted except afragment on one side.

Fig. 5 is a crosslsection on theline B-B of Fig. .1, the windings being omitted.

Fig. 6 is an enlarged fragmentary section across one of the slots of the finished armature.

Fig. 7 is a simplified of elementary diagram of the armature winding, an equal number of slots and commutator segments being shown and each coil being represented by a single turn or loop.

In the construction shown in the drawings, the laminated drum or core 1 consists of soft iron plates 2 held together on the shaft 3 in a manner usual for small armatures. Preferably the laminae 2, and also the insulating and plates 4 at the ends fit tightly on the shaft, so as tobe secured suflicientlyby friction. The adjacent parts of the shaft are covered with insulation 5,

such as tape or the like, which further holds the plates 4 in place. Saidcore 1 is provided with transverse slots 6 preferably disposed at a slight angle, or somewhat spirally, as usual in armatures, said slots being produced by providing suitable notches in the plates 2 and 4: whenthey are punched from sheet stock, 'and then duly alining same on the shaft 3 when assembled, as will be understood.

' Each slot G is relatively deep and narrow and has a restricted opening or mouth 7 having thin overhanging flanges or lips 8.

The corresponding intermediate teeth 9 are also relatively tal and narrow and are T- shaped. When the armature is finished, each slot contains overlying parts of two separate coils or bundles 10 disposed widely apart electrically, prefera ly nearly one hundred and eighty electrical degrees, one coil being disposed in the bottom of the slot and the other adjacent to the month, said coilsbeing thoroughly insulated from each other and'from the .core 1.

The insulating means provided in each slot includes a slot lining member 11 of U-sh'ape (see Figs. 5 and 6), against which the inner or bottom coil is dis osed, and

an inner member 12 having its e ges turned convergently in a more nearly tubular or cylindrical shape, wherein the outer or top .slots 6,, including the end insulators 4, so

that the coils are thoroughly insulated from thecore. The key 14 may consist of fiber board, or suitable wood may be used. The number of slots may be varied according to the size of armature required, nineteen being providedin the present embodiment, said slots being numbered in order from 1 to 19 (see Fig.7). v The armature is slot wound and the coils 10 are arranged on the drum-like core in the form of a drum winding, which is applied as follows: First, the insulators 11 being in place, eight coils are disposed in direct regular order in certain slots, Nos. 1 to 8 and 9 to 16 for the opposite sides respectively (see Figs. 6 and 7). Then a layer of suitable insulation 16, preferably silk tape, is applied or wound in like manner directly over said coils. Part of the insulators 12 are next inserted, over the coils already in place. A second group of eight coils is then applied, being disposed in a similar manner successive to and in series With the first coils, but in slots 9 to 16 and 17 to 5 for opposite sides respectively, and partly overlying the first group of coils. A layer of insulation 16 is then applied over the second group of coils. Then the rest of the insulators 12 are inserted. Finally, a third group of three coils is applied in like manner in certain slots, 17 to'19 and 6 to 8 for opposite sides, and a layer of insulation 16 is applied thereto. A final outer protective layer of tape may well be added over all. The heads of the armature being thus protected with silk tape present a smooth rounded surface,-hence the term bald head which is the shop term applied to these armatures.

The armature may be machine wound to advantage, as by means of a suitable chuck and appliances understood by those skilled in the art, the windings being continuous and commutation loops 17 being formed at the commutator end of the slots, said loops preferably being provided with protective sleeves 18 of suitable woven fabric leading from the slots 6 to the corresponding segments 19 of the commutator 20 (see Figs. 1, 2 and 4).

On account of physical limitations, and commercial efficiency in manufacture, the number of slots on a given armature is usually less than would be preferred from a commutation point of View. Hence, in order to minimize sparking, the commutator is preferably provided with more segments than there are armature slots, the number of segments being some multiple of the number of slots. In the drawings (except Fig. 7), there are three times as many segments as slots, or fifty seven segments, and each coil or bundle comprises three equal parts connected in series to three corresponding segments. Hence when any two adjacent segments are connected or bridged by a brush, only one third of a complete coil or bundle is short circuited, instead of a whole coil.

As there are three loops 17 leading from each slot, each inclosed in a separate sleeve 18, said sleeves arev distinguished in regular order according to a simple code, for in stance red, white, and green sleeves being used respectively. Then when the winding is finished the color code indicates to which segments the several loops are to be soldered respectively in connecting the coils to the commutator.

The insulation provided by the medial layer of tape 16 overlaps itself in .an increas: ing degree approaching the center or shaft 3 which provides a multifold protection against grounding of the armature coils against the frame or bearing bracket of the motor, through the inevitable accumulation of conductive dust and like foreign material. In the embodiment shown it is to be noted that the difference in potential between adjacent coils, inner and outer, is about nine tenths of the entire impressed voltage, so that when the full maximum of 1000 volts is applied to the brushes the insultation betwen coils must withstand about 900 volts. When the windings and insulation are all in place the armature is thoroughly impregnated with varnish and baked, whereupon it must stand an insulation test of about two thousand volts to the shaft or ground.

One of the more important uses for motors having armatures embodying this invention is for operating accessory devices used in connection with direct current street railway equipment, especially where the motor current is taken directly from the railway power circuit. Certain parts or features of theinvention may be used on low voltage high speed (3000 to 4000 R. P. M.) armatures to keep machine wound windings in position against centrifugal force, reduce 100 the windage friction and exclude dirt, which tends to deteriorate the windings. For such work the motor is preferably compound wound, though a simple shunt motorembodying the invention may be used.

Although but one specific embodiment of this invention is herein shown and described, it will be understoodthat numerous details of the construction shown may be altered or omitted without departin from the spirit 110 of this invention as defined y the following claims.

I claim: a

1. A drum wound slottedarmature adapted for high potential direct current, and hav- 115 ing a continuous winding disposed in its slots, said winding being arranged in the form of and comprising a plurality of coils disposed one over another in the slots, with a correspondingly disposed winding of tape 120 insulation between adjacent coils.

2. A slot wound direct current armature having a continuous closed circuit windincg including a set of coils the opposite si es of which are disposed in slots nearly 125 one hundred and eighty electrical degrees apart, successive coils being disposed in im mediately successive slots respectively, and and a pair of conduit-like insulation members in each slot for housing the adjacent 130 shaped lining of insulation for said slot, a

coil having one side disposed in the bottom of saidslot, an insulating strip resting on said coil and having its edges turned outward and convergently to form a'tubular casing or conduit, a second coil of widely different potential from the first mentioned coil and having One side disposed in said casing and a rigid key fitting tightly between said casing and said lips for securing said coils in place, and complete windings of tape immediately overlying said coils respectively.

4. A direct current slot wound armature having tape wound .over the coils and across the ends and varnished and adapted to hold.

the coils in place at the ends, said ends of the armature being rounded and presenting a bald head appearance and being adapted to minimize Wmdage friction, same beenig adapted and arranged to seal up the h and so prevent grounds.

5. A slot wound armature of the character described, comprising a plurality of coils arranged in the slots and connected in closed circuit, each slot containing one side respectively of each of two separate coils disposed approximately one hundred and eight electrical degrees apart, and a winding 0 insulating tape disposed between adjacent coils to prevent electrical short circuiting.

6. The method of winding a bi-polar slotted armature which consists in winding into the slots and across the core ends coils of insulated conductors alternately with correspondingly disposed complete turns of tape insulation.

Signed at Chicago this 24th day of July 1916.

JOHN w. PEARSON. 

